Measurements of the position of the axis of inertia of a workpiece or machine part designed for rotation are taken in a process referred to as balancing or mass-centring. In this process, the workpiece is received in a machine in an initial position predetermined by its geometrical shape and rotated around the thus given axis of rotation. While the workpiece rotates, any existing unbalance is measured, and the position of the axis of inertia of the workpiece in relation to the given axis of rotation is determined. A further step comprises varying the bearing support of the workpiece such that the given axis of rotation and the axis of inertia coincide. In this position, locating bores or similar centring means are provided on the workpiece, which serve to locate the workpiece in the subsequent processing steps.
DE 10 2007 018 618 A1 discloses the structure of an exhaust gas turbo-charger constructed to include essentially a radial turbine having a turbine wheel and a compressor having a compressor wheel connected to the turbine wheel by a shaft in a manner preventing relative rotation. A problem presenting itself in the mass-centring of turbochargers is that the turbine wheel is frequently provided with a prior cast centre in consequence of which centring has to be performed in this centre. Performing centring with a drill frequently results in deviations from a desired position. Alternatively, centring may also be done by means of a grinding spindle.